Breech block for firearms



Sept. 13, 1955 A. MARcATl 2,717,464

BREECH BLOCK FOR FIREARMS Filed May 2l, 1951 IN VEN TOR. /4/1/ 7' /V/ MARC/477 we, vnf/M BREECH BLCK FR FREARMS Antonio Maronti, Buenos Aires, Argentina, assigner to Gildo Marcati, Buenos Aires, Argentina Application May 21, 1951, serial No. 227,403

s claims. (ci. i2- 16) This invention relates to improvements in automatic or semiautomatic firearms, and has as one of its main objects to provide means resulting in a substantial simpliiication in the construction of the breech mechanism together with the tiring-pin and the recoil spring.

In automatic or semiautomatic firearms in which the reaction of the cartridge case results in the displacement of the breech block, which has to overcome the resistance opposed by the mainspring so as to return the block to its original or starting position, the design of said block and its actuating pieces, such as the firing-pin and the recoil spring, becomes very important. The wear of the material must be kept to a minimum and undesirable working stresses are to be eliminated, which appear when the different parts operate under unusual working conditions.

The fundamental features which should be taken into consideration for the construction of the breech block and its accessories are: the general dimensions of the assembly should be reduced to a minimum consistent` with the mass required so that the inertia of the moving pieces delays the opening of the combustion chamber until the bullet has left the barrel; and the assembly and disassembly of the breech block should be as simple as possible.

The first of these features greatly aiects the weight of the firearm on permitting the reduction of the dimensions of the housing in which the breech block runs. In this sense the limit has been practically attained, by making the recoil spring reach the breech block farther than the back of the hammer. For this purpose the recoil spring is arranged almost on the surface of the breech block, the hammer being in an oblique position relative to the block axis. The foregoing arrangement used in some of the lire arms known up to the present, has the disadvantage, since the recoil spring is eccentrically operated, of needing a perfect adjustment between the block and the case, if the uneven wear originated by the eccentric impulse is to be reduced to a minimum; moreover, the hammer working in an oblique way is subject to considerable transverse stresses which rapidly bring about weakening and weariness of the material.

With respect to the assembly characteristics, the problem is directed almost solely to the recoil spring because the latter presents most of the difficulties for its mounting since it should be installed in most cases in compressed state which means a risk for the operator if he does not have adequate tools available. Recently, a good solution has been found by employing a telescopic capsule that houses the recoil spring, but the manufacture of same is rather complicated and results in high production costs.

It is an object of the present invention to provide a new arrangement of the recoil spring with respect to the ring-pin, all within the bolt, or the breech block, which allows the firing-pin to be mounted parallel to the block axis.

A feature of this invention resides in the fact that the 2,717,454 Patented Sept. 13, 1955 recoil spring is totally confined in the breech block, surrounds the tiring-pin, and bears with one end against a rod, slidable in a bore of the block. The other end of the rod rests against a portion of the housing or chamber of the breech block. The axis of the spring, the rod and the breech block and the ring-pin may be the same.

Another feature of this invention is that the rod, against which one end of the recoil spring bears, has at its front end an interlocking projection, or other means which cooperates with a stop or projection arranged in the rear part of the tiring-pin, so that release of the spring, and said rod, is prevented, and the bolt or breech block may be disassembled from the rearm as a unit without manipulating the spring.

Still a further feature of this new device is constituted by the provision of means to limit the travel of the firingpin with respect to the breech block. This limiting means acts as a stopping means for the recoil spring, keeping it assembled within the breech block and to the firing-pin and the spring rod, thereby facilitating fieldstripping and clearing of the rearm. y

The invention will now be described in greater details in the following description of one of its preferred forms of construction, which has been illustrated in the attached drawing and in which:

Fig. l shows a longitudinal section of a breech block for an automatic or semiautomatic Carbine, constructed in accordance with the present invention.

Fig. 2 illustrates a transverse section of said breech block taken along lines 2 2 of Fig. 1.

Fig. 3 shows a similar section taken along lines 3 3 of Fig. l.

Referring now to the drawing, and particularly to Fig. l, there is shown a bolt or breech block 1 of generally cylindrical shape which is disposed in a housing or chamber 2, (partly represented in dotted lines) and in which said block may freely move. The chamber is closed at one end by a removable back cover 2a. The bolt 1 is provided on its front face 5 with an extractor 3, which engages the rim of a cartridge in the usual manner during the recoil of thepblock. An ejector (not shown) may also be provided in a conventional manner. its lower part, the breech block 1 is provided with a series of recesses 4, which allow the front face 5 of l block 1 to pick up and push a new cartridge from a magazine into firing position. The breech block 1 isi hollow, as shown, having a longitudinally extending bore 6 terminating at its front end in a perforation 7 of lesser diameter to thereby form a shoulder in said bore 6; the shoulder in bore 6 thus constitutes a seating surface 8 on which one end of a recoil spring 9 is supported; spring 9 sur` rounds the pin 10 acting as guide means for the tiring-pin. The tiring-pin 10 is entirely enclosed in the breech block and ends in its rear part in a bifurcated jaw 11 which projects beyond spring 9 to slide in a slot 12 in the block 1; in the mouth 13, formed by the bifurcated jaw 11, a holding pin 14 is loosely disposed in a transversely extending slot 15. The pin 14 has its ends formed with the same curvature as the bolt 1 (Fig. 2); pin 14 will therefore be retained in the bolt 1 by the wall of the chamber 2 as can be visualized from Fig. 2. The pin 14 acts as a stop for the stroke of firing pin 10, the jaw 11 being normally pressed toward it by the spring 16 urged against finger or prong 17, which bears against the outside face of jaw 11, as shown in Fig. 1.

The tiring-pin 10 is preferably of square cross-section and passes through an eye 18a of equal cross-section made in the front end of a grooved rod 18, this rod 18 serving as a means of support or abutment for the opposite end of the spring 9. Rod 18 is formed with a groove 19 as a guide for the firing-pin 10. The external contour of the rod 18, in this case of circular shape, is formed to. match the bore 6 into*A which (during the recoiling traveLof. the block. l). the. rod 18. extends. A recess.20 made in the lower end of therod 18 allows the hammer 21 to reach the jaw 11 of the firing-pin 10 at a convenient height.

Theassembly` isprovided with a handle 22 which. is disposed transversely ofthe block, 1' and received therein (see Fig. 3*). The inner partof handle 22 is formed with `a recess having thersarne form as the wall. of the bore 6;l externally of the block 1 the handle has a notch 24 running in azlongitudinal groove of the wall of the chamber 2; this handle permitsmanual, external operation of the breech block.

The operation of the various pieces mounted on the breech, block isrestricted to the.inward movement of the tiring-pin` -when the hammer 21 strikes the back of the jaw 11` tothereby overcome the tension of spring 16 in such a way that the tip of the tiring-pin 10, protruding beyondspring 9.- andthe frontofv the block 1, strikes the cartridge case. The explosion. of the cartridge causes recoil movement ofthe block 1 against tension of spring 9, and further penetration of the rod 18 into the bore 6, the flring-pin 10 sliding in the. groove 19.r This recoil movement alsocauses the compression of the spring 9 between the seat 8 andthe front end of the rod 18l as well as the rotationof. the hammer 21 to the tiring position. The ,energy accumulated in thespring 9 pushes the block 1 inward which results in feeding the chamber with a new cartridge, thus the block being ready to fire again.

Todisassemble the mechanism, the back cover 2a of the. chamber Z'isv removed which permits a little expansion of the spring 9 until the rod 18 is stopped in front of the jaw 11; jaw- 11 is held-in the breech block 1 by the pin 14 which alsoV prevents the ringapin 10 from running out backwards. In this condition the assembly is locked together and can be withdrawn from the rear of chamber 2 as a unit, without the risk of having the spring 9 shootk oif. Once the breech block is removed from chamber 2, the pin 14 can be removed from its seat in slot 15, thus freeing' the jaw 11 and? permitting the withdrawal of thering-pin 10 and the easy disassembly of all the pieces. For the assembly one proceeds in a reverse order.

It should be `understood that the description, as well as the attached drawing are set. out4 only as a demonstrative form and-not limitative, it being permitted to introduce any kindof modifications in appearance, construction and detail not exceeding the scope of the invention such as defined in the following claims.

I claim:

1. In a rearm; a breechhousing, an elongated breech block slidably mounted lengthwise ofand relative to said housing,.said breech block having at one end thereof a.

front face adapted to bear against a cartridge and a rear portion at the other end thereof, said breech block having a bore extending from said rear portion of said breech block in substantially longitudinal direction of the latter toward said front face and terminating short thereof, said front face having a relatively small aperture coaxial with said bore and communicating with the latter, a tiringpin disposed in said breech block andV movable in said bore, said firing-pin having a rearward portion and a forward portion, an elongated recoil spring completely seated within said bore and guidingly surrounding the major portion of said firing-pin, said forward portion of said firing-pin extending beyond' said recoil spring into said aperture and being adapted to strike against a cartridge, an elongated rod having a forward end and slidably mounted in said bore relative to said tiring-pin and bearing against an end of said recoil spring, said forward end of saidrod encircling saidrearward portion of said tiring-pin adjacent said spring, said rearward portion of said firing-pin including an enlarged end, said forward end of said rod including means interlocking with said enlarged end of said firing-pin, and means operatively associated with said breech block and disposed in the path of sliding movement of said tiring-pin between said forward end ofV said rod and adjacent said enlarged end of said ring-pin to prevent disassembly of rod and breech block.

2. A rearm according to claim l, wherein said operatively associated means includes a holding pin removably mounted in the breech block and extending substantially in transverse direction to and below the axis of said firing pin, said enlarged end of said firing-pin including a bifurcated jaw for receiving Said holding pin.

3. In the rearm according to claim l, wherein said forward end of said elongated rod includes an eye operatively receiving the tiring-pin forwardly of the enlarged end thereof.

References Cited in the file of this patent UNITED STATES PATENTS 357,170 Bjerkness Feb. 8, 1887 561,617 Schmeisser June 9, 1896 984,489 Redfield Feb. 14, 1911 1,460,672 Hines July 3, 1923 2,072,197 Bergmann Mar. 2, 1937 2,242,389 Burton May 20, 1941 2,565,688 Horan Aug. 28, 1951 

